The use of mobile computing devices has become increasingly widespread. Although lightweight and small, the portability of modern mobile computing devices often means small keyboards or other types of input devices that many users have difficulty using. Some mobile computing devices include a feature that allows the user to interact with the device using speech. For example, a user can place a telephone call to someone in his or her contact list simply by speaking a voice command (e.g., “call”) and the name of the contact into the device. Distinguishing the user's speech from background noise can be difficult in some environments. Additionally, it can be challenging to begin recording speech at the right time. For example, if recording begins after the user has started speaking, the resulting recording may not include all of the user's voice command. Furthermore, this may result in the user being notified that a voice command was not recognized by the device (because it was only partially received), which can be frustrating for the user.